Electrode for arc-lights.



UNITED -sT-ArEs PATENT oEEroE.

FREDERIC JULIUS GERARD. OFLON'DON, ENGLAND), A'SSIGNOR OF ONE- HALF TO LOTHAR FIEDLER. OF LONDON, ENGLAND.

- EtEoTioDE Fon ARC-LIGHTS.

Be it' known that I, FEEDER] -I'Us GE- RARD', of 54 Delancey street, London, England, have invented certain new and useful Improvements in Electrodes for Arc-Lights; and I do hereby declare the following to be a full; clear, and exact description of the invention, such as will enable others skilled in the vart to which it appertains to make and use to' the same; The accompanying-drawing shows an elevation of the electrode. This invention relates to improvements in the composition of electrodes for use in arclamps, Wherebyin proportion to the expenditure of electric energy there Will be an increase in the brilliance 'of the light emitted and a greater uniformity in its' intensity. These advantageous effects are derived by the use ofA magnesium in the composition of the electrodes, Which, While yielding the brilliant white light due to the intense incandescence of its oxid in the process of burning, is introduced under such conditions as to cause its natural high rate of combustion .to

, be restrained to conform with the rate of combustion of the other substances of which the electrode is composed and result in a slow uniform consumption, avoiding the accumulation of` incrustation.

I am aware that metallic magnesium and chemical com ounds containing magnesium have previous y been used mixed with carbon and other substances in the composition of electrodes for arc-lamps and that it has been proposed to electrolytically deposit a coating of magnesium and aluminium or alloys thereof on such electrodes; but hitherto the magnesium has been so associated or so unassociated that it could and always did take advantage of its superior aliinity for oxygen and burn more rapidly than its com panion material, resulting in too high a rate of combustion and considerable fluctuations of light due to accumulations of those other substances. According tomy invention I am able to avoid this'either by introducing the magnesium' in the form of an alloy with one or more other metals 'or as a mixture of substances so selected and assembled as to require a metallic alloy containing ma nesium to be produced by the combined e ect of electricity and heat on those substances immediately preceding-.its combustion in the Specification of Letters Patent.

' linea June 9,1902. smaila; 160.760.

` Patented Aug. 14, 1906.

electric arc. The former method is under ordinary circumstances the preferable one;'"

.Hence it will be easyto adjust the proportions toobtain the most advantageous rate. About half and half gives a good result. The alloy is preferably introduced into the electrode in the form ofa finely-divided metallic powder intimately .mixed with the carbon and other materials of the electrode, for thereby the electrode will be rendered more conductive and more uniform in its conductivity, thus effecting a steadier illumination.

Inasmuch as metallic magnesium can be derived by the reduction of magnesium com-V pounds suitably associated With other substances by means of electric agency and heat,

it is possible to form the alloy in the electrode at the instant prior -to combustion, and thus Aachieve, the result previously described of restraining the rate of combustion of the magnesium. If, for example, chlorid of magnesium is intimately mixed with powdered metallic aluminium and the mixture Worked up with carbon in forming an electrode, the nascent magnesium resulting from the reduction of chlorid Will at the temperature lin the neighborhood of the electric arc before etting into contact With oxygen readily a loy with the aluminium by its side.

It will be possible to effect the formation of the alloy by suitable mixtures of the magnesium compound with compounds of ,other metals not in the metallic state; but in such a case the benefit of the increased conductivity of the electrode derivable from the admixture of metallic powder will be absent, so that the other substances introduced to form the alloy with magnesium should preferably be in the form of metallic powder, while the magnesium substance, except in the form of an alloy, should not be metallic.

Uniformity of action will be insured by the use of a minute proportion of a salt of one of the rare earths, preferably cerium nitrate. This substance appears to act in such away as to prevent incrustations being formed on the IOO electrodes, which otherwise after long intervals may be liable to occur from an accumulation of the oxi'ds of the metals. the presence of the cerium nitrate is to cause the oxids to be carried off as powder.

I claim- *Y 1. An electrode for arc-lights comprising 'an intimate mixturerof carbon with an allo consisting of ma nesium and another meta 2. An electro e for arc-lights comprising an intimate mixture of carbon With an alloy consisting of mavnesium and aluminium.`

3. An electro e for arc-lights comprising an intimate mixture of carbon with a small percentage of a salt of a rare earth and an allo? consisting of magnesium and another meta The efect of 4. An electrode for arc-lights comprising an intimate mixture of carbon With a smal percentage of eeriun nitrate and an allo consisting of ma nesium and another meta zo `5. An electro e-for arc-lights comprisin 'an intimate mixture of carbon with a s'ma percentage of cerium nitrate and an alloy consisting of magnesium and aluminium.

In testimony whereof I have hereunto set 25 my hand in thepresence of two subscribing Witnesses.v

FREDERIC JULIUS GERARD.

`Witnesses:

THOMAS ALFRED HEARsoN. WALTER J. SKERTEN. 

